1. Technical Field
The present invention relates in general to data processing systems and in particular to identifying analog devices. More particularly, the present invention relates to providing identity and/or calibration information of the analog device to a control system.
2. Description of the Related Art
It is a common practice in industry for Original Equipment Manufacturers (OEMs) to rely on third party vendors to supply replacement parts for computer associated systems. OEMs provide standards for third party vendors to build the replacement parts and generally, OEMs provide the parts to the customer. However, customers will purchase and install xe2x80x9cequivalentxe2x80x9d parts because of price. xe2x80x9cEquivalentxe2x80x9d parts may be approved by the OEM for replacement, but not carry the same quality control requirements of the OEM. Replacement parts may have variances in the part, but depart from the OEMs specification and require installation service to coordinate the part to the control system. Additionally, an OEM may update or improve a replacement part that performs the same task as the original part but it may have altered tolerances or specifications that require system adjustment upon installation.
In data processing systems, storage subsystems are constantly undergoing improvements. In tape drive storage subsystems, one of the target areas is in improving the tape. Thinner tape has been developed in order to increase data storage and keep tape cartridges the same size for existing tape drive systems. Thinner tape allows more tape to be wound on the same cartridge and thus, increases memory storage for a standard tape drive cartridge. However, thinner tape increases the likelihood that tape breaks will frequently occur because drive motor assemblies for the cartridges were built and tensioned to operate with thicker tape. Economically, customers using tape drive storage would prefer increased storage via improved tape rather than new storage systems because of the replacement cost involved. So, manufacturers of tape drives provide Engineering Changes (EC) and retrofit solutions that will account for the thinner tape.
For instance, the 3590 Magstar(trademark) tape drive, a product of International Business Machines of Armonk, N.Y., required a hardware change to a tension transducer assembly in order to handle new, thinner tape than the standard tape. It was necessary to make changes in the field without requiring the customer to make hardware modifications. Therefore, it was desirable to have microcode available on the new tension transducer assembly that included the mechanical properties of the new transducer. Because this was a field change, hardware had to go into existing drives and no changes could be made to the rest of the system.
For example the function of any of the pins on the new transducer card could not be re-assigned nor could any wires be added to the connector cable. Further, the card had to function normally with old microcode so that the assembly could be put into old drives without affecting their operation. The new transducer cards also have to be used as spare parts for old drives and have to function like the old ones so that the code would not have to be changed to support the new hardware.
The tape drive tension transducer card has a single output. This output is the analog tension signal to the drive motor servo controls. Voltage level output is proportional to the tension detected in the tape. There are no other signal sources or outputs available. Using a DC offset voltage to distinguish the old and new cards does not work, because the signal may not be large enough to allow reliable determination of old and new sensors. Also, if the offset is too large, the signal adversely affects operation of a servo system associated with the tape drive. Utilizing voltage level to distinguish between old and-new transducers is unreliable because the voltage difference between the two signals is too small.
Principally, the tape drive tensioning problem revolved around availability of a single source that is currently utilized to supply an analog signal. There are no other connections that may be used for identification of a replacement hardware device in this area. So, in order to improve the storage capacity of an existing tape drive storage subsystem, a customer its required to install new hardware and adjust the control system to fit the new hardware.
In general, data processing (computer) systems that control and monitor analog devices are constantly being improved and upgraded by OEMs. OEMs that manufacture process control systems offer improved parts and subsystems to customers with older, existing installations. The new parts usually require additional hardware, new procedures, customer installation, etc. Third party vendors are also improving individual subsystems that would improve operation of these computer control systems such as increasing the life of the system, enhance control, improve efficiency, etc.; all economic benefits to the system user. A problem similar to the OEM problem is caused by new and improved parts from third party vendors in that system parameters may have to be changed to incorporate the new parts.
Therefore, it would be desirable to provide a method and apparatus that will provide self-identification for a newly installed analog hardware assembly to a data processing system to which the assembly is being installed. It would further be desirable to provide a method and apparatus that will identify, provide operating characteristics and provide configuration parameters of an analog device to a digital control system.
It is therefore one object of the present invention to provide a method and apparatus to provide identification of an analog device to a control system.
It is another object of the present invention to provide a method and system for calibrating analog systems without requiring additional wiring for configuration purposes.
It is yet another object of the present invention to provide a method and apparatus for verifying the presence of a device without causing interference in the analog circuitry.
The foregoing objects are achieved as is now described. A microprocessor (or generically, digital state machine and timer) with microcode is incorporated in a mechanical device, having analog electrical signaling wires, to send a digital signal containing identifying data of the device to a central computer. The digital signal includes operating ranges and any other information that will allow the central computer system to recognize the mechanical device and automatically incorporate the device""s operating characteristics into the total system without disruption. The digital signal is transmitted to the central computer system immediately after a power-on signal is detected by the microprocessor on board the mechanical device.
The above, as well as additional objects, features, and advantages of the present invention, will become apparent in the following detailed written description.